Time of day for taking medication?

At night during sleep, it tends to drop again, by about 10% to 20%. But blood pressure can behave differently for some people with HIGH blood pressure, and four distinct patterns are recognized:

Those that experience a normal drop in blood pressure of 10% to 20% (normal dipping)
Those who experience extreme dipping – a drop of more than 20%
Those who hardly dip at all (non-dipping), which is a drop of less than 10%
And those who experience reverse dipping – where their blood pressure is higher during sleep than while they are awake.
The only way to know if your blood pressure changes at night if you are not awake to measure it, is to wear an ambulatory blood pressure monitoring device for 24 to 48 hours, which measures your blood pressure regularly throughout the day and night. Ask your doctor about this.

Studies have shown that people who experience non-dipping, reverse dipping, or extreme dipping have a higher risk of cardiovascular disease events than those who experience normal dipping, and these people may benefit from taking their blood pressure medications at night because it normalizes their blood pressure. People over the age of 55 are more prone to non-dipping.

The Hygria chronotherapy trial reported that those who switched their blood pressure medications from morning to night experienced:

A 44% drop in heart attack risk
A 40% reduction in the risk for coronary revascularization (surgery to widen the coronary arteries)
A 42% lower risk for heart failure
A 49% reduction in the risk of stroke.
But you should not change taking your blood pressure from morning to night without talking to your doctor first. Some blood pressure medications, such as diuretics (fluid pills) are best taken in the morning because they increase how often you urinate, and you don’t want to be getting up multiple times during the night. Also, if you find it easier to remember to take your medicine in the morning, then keep taking it at that time because swings in blood pressure from forgetting to take your medicines increase your risk of a cardiovascular event more than elevated blood pressure. If you work shift work, it is better to take your blood pressure medication before you go to bed - which ends up being in the morning for most people. Switching your medicine from morning to night may not offer the same beneficial results for everyone.

The Hygria chronotherapy trial followed 19,084 Caucasian Spaniards with high blood pressure for an average of 6 years. Half the group took their blood pressure at bedtime while the other half took it in the morning. People who took their blood pressure medication at night had overall better blood pressure control and were less likely to have a cardiovascular event, such as a heart attack or stroke.